Upgrading is the processing of bitumen, heavy oil or hydrocarbon residues to produce a better quality crude oil product. The upgrading process can result in a synthetic crude product with reduced viscosity which may be transported by pipeline without a diluent, a product with reduced density to produce an economically more valuable product, and the removal of contaminants such as metals and sulphur.
The reactions used to upgrade bitumen fall mainly into two different categories. First, thermal cracking reactions use heat to drive the upgrading process, usually with the formation of coke. Fluid coking is a thermal conversion process where long chain bitumen molecules are cracked into more valuable short chain molecules. It is a continuous operation where fluidized coke particles are transferred back and forth between the reactor and burner vessels. A portion of the coke produced in this process is transferred to the burner to provide heat for the thermal cracking process. The second category includes catalytic reactions with hydrogen gas.
A hydroprocessing unit such as an LC-Finer™ is an example of an ebullated bed catalytic hydrocracker. The principal advantage of hydrocracking technology compared to fluid coking is the ability to convert microcarbon residue (MCR) into distillable products and hydrogen-rich pitch materials. As such, the greatest benefit of the hydrocracker is realized when the maximum possible pounds of MCR are converted; improving the yield of synthetic crude on each barrel of bitumen processed.
In one commercial operation, fluid coking and hydrocracker processing have been operated in parallel, where both the fluid coker and the hydrocracker process a mixture of atmospheric topped bitumen and vacuum topped bitumen. The unconverted hydrocracker bottoms have then been processed in the fluid coker. However, hydrocracker throughput has been limited by the pumping capacity of the hydrocracker bottoms to the coker and the reactor exotherm. The presence of hydrocracker bottoms arises from unconverted pitch in the product stream. Reactor exotherm arises from the consumption of hydrogen due to removal of heteroatoms (primarily sulfur, nitrogen, nickel, and vanadium) and hydrogenation (i.e. saturation of aromatics, olefins/free radicals resulting from boiling point reduction, etc.).
The focus on improving performance of hydrocracking technology has typically been on developing improved activity catalysts for the feed, which is typically a mixture of atmospheric topped bitumen and vacuum topped bitumen. However, there may be an opportunity to improve hydrocracker throughput and conversion by improving the feed quality.